I purchased CS3 complete and included was Acrobat 8 Professional. It has been working since 2008 up until middle of January when i decided to download a trial version of CS6. I then after the trial period decided i didnt like it and wanted to go back to my previous version. I have found that i cannot use my Acrobat 8 preffesional as i cannot now reactivate it and i have had 2 months of getting the run around with Adobe.
Not a happy customer.
You might want to try clean installation. Here's the link on how to do it. http://tweakccm.blogspot.in/2013/03/tips-tricks-on-manually-cleaning.h tml
Hope that helps